Scientists are coming up with less-toxic ways to manufacture everything From decaf coffee to plant pesticides.
In the 1950s and the post-war boom of optimism and innovation, the spirit of the times was captured in one simple mantra: better living through chemistry. With boundless faith in the potential of modern science, chemists cooked up new concoctions that promised to make our lives easier, safer and more comfortable. Pesticides that rid our crops of insects. Refrigerators that kept our food fresh. Drugs that eased our pain and suffering. But there was a problem: many of these innovations had unforeseen and disastrous consequences. Pesticides decimated bird populations. CFCs from discarded refrigerators bore a hole in the ozone layer. And billions of tonnes of hazardous-waste by-products were flushed into the environment, with some eventually ending up in our own bloodstreams.
So we started to ban hazardous chemicals, from DDT to PCBs. That process is ongoing – though perhaps not as quickly and thoroughly as we might wish. The federal government undertook a mammoth review of 23,000 chemicals under the Chemicals Management Plan, then decided 4,000 needed further attention. Of those, 200 – the ones identified as being potentially the most hazardous – are under review, with the results to be completed some time in 2009. But say we decided to eliminate every single dangerous chemical we use. Are we really willing to live without all electronics, including computers, because their manufacture requires harsh solvents? Do we really want to eliminate all plastics, including medical supplies? Are we going to scrap research for new cancer drugs because it produces toxic waste?
Enter green chemistry
This new branch of science is allowing us to have our cake and eat it too. By designing new compounds and discovering new ways to make old compounds, chemists are helping us keep our modern innovations while reducing our ecological footprint. “You can look at hazardous emissions and toxic products and examine their impact,” says Beverley Thorpe, the Montreal-based international director for Clean Production Action. “But the ultimate question is how to transform our toxic-chemical economy into one that is safe and healthy, and green chemistry is going to play an absolutely critical role in that.” Although the phrase “green chemistry” has only been around since the early ’90s, scientists have been practising it for many years. Forty years ago, for example, piles of fluffy white foam were a common sight in rivers all over Canada, because industrial and kitchen soaps wouldn’t decompose once we flushed them down the drain.
So chemists rejigged surfactants so they would stay intact long enough to clean our clothes but could be degraded by bacteria once they reached the sewers. Another key example, and one Canadians can be proud of, is the phase-out of CFCs – chemicals that were used as refrigerants and in propellants in cleaning solvents – under the 1987 Montreal protocol. Thanks to global public pressure, industries all over the planet were forced to create new substances that worked just as well as CFCs but wouldn’t destroy the ozone layer. Today, chemists are striving more than ever to green manufacturing operations, by reducing energy use, employing non-toxic solvents, eliminating waste and using renewable resources as ingredients. “We’re fighting on a lot of different fronts at once,” says Professor Audrey Moores, a Canada Research Chair in Green Chemistry who teaches the subject at McGill University in Montreal. “So you can’t really say that a new chemical or process is ‘green,’ only ‘greener.’ We’re trying to address a terribly complicated issue, but it’s definitely worth trying – our planet will be in big trouble if we don’t.”
Getting rid of toxins
Challenging as this task may be, by cleverly redesigning things from the atom up, green chemists have discovered new reactions and created new products that are safer and cleaner while being just as effective (if not more so) as the old methods. Take the fire extinguishers developed by Pyrocool Technologies. Many traditional fire extinguishers release toxic fluorine-containing compounds, but Pyrocool’s versions are non-toxic, biodegradeable and, best of all, effective at about one-tenth the concentration of old-school foams. Green chemists have also been able to put a new face on pesticides. The biocide Messenger, made of natural, non-toxic proteins, triggers a plant’s natural defence system to fight off viral, fungal and bacterial diseases. And Serenade – a fungicide containing a natural strain of bacteria – is even approved for use in organic agriculture.
Redesigning chemicals to reduce our use of fossil fuels is another important focus. Bioplastics, for example, are made from plants instead of fossil fuels. They look and feel like normal plastic but will break down in landfill or compost. And the ability to make bioplastics is having an impact. Retail giant Wal-Mart, for instance, is starting to use corn-based bioplastics to package some of its products. And where Wal-Mart goes, other stores will likely follow. Green chemistry can also be used to make green processes even greener. Recycling different kinds of paper can actually damage the environment because harsh solvents are needed to remove adhesives on envelopes and sticky notes. But the synthetic enzyme Optimyze can be used to remove the glues instead. A typical mill in a year can reduce the amount of solvents used by 276,000 litres and save up to $1-million. This is one of the key paradigm shifts in green chemistry and, indeed, in the green movement generally: in the end, it can be much, much cheaper to be green. “If you create pollution, you have to spend money every year for the cleanup and hazardous-waste disposal,” says Professor Philip Jessop, a Canada Research Chair in Green Chemistry at Queen’s University in Kingston, Ont. “But if you invest the money beforehand to minimize your impact, you’re going to spare your pocketbook as well as the environment. The old idea of green chemistry being a waste of money is wrong – it’s a way of saving money.”
Carbon dioxide: from waste to resource
Another way green chemistry is turning conventional chemistry on its head is in coming up with ways to use carbon dioxide (CO2) as a resource. In order to limit our greenhouse-gas emissions and slow global warming, soon we’re going to have to collect CO2 as it spews from industrial smokestacks, rather than vent it into the atmosphere. Some schemes call for it to be stored, perhaps underground. But instead, asks Prof. Jessop, “Is it useful for anything? Can we recycle it like we do with waste paper?” Indeed we can. One of the most important innovations to come out of green chemistry is the use of what’s called supercritical CO2, which is between a gas and a liquid. Coffee beans, for example, used to be decaffeinated using dangerous chlorine compounds. Now most European coffee companies (and a few North American ones) remove caffeine with supercritical CO2. Even more impressive, American company NovaSterilis Inc. has come up with a way to use supercritical CO2 to sterilize biological materials such as graft tissue and vaccines, which previously were kept free of bacteria with ethylene dioxide or gamma radiation, both dangerous as well as ineffective at preserving the integrity of delicate biological tissues. Supercritical CO2 is neither.
Prof. Jessop is researching ways to use CO2, for the manufacture of pharmaceuticals, one of the most wasteful of all industries. Modern drugs contain extremely complex molecules that can require dozens of different reaction steps to produce the final result. “For some drugs, if you take a gram of that medicine, that means as much as six kilograms of waste ended up somewhere,” he says. Looked at on a larger scale, every kilo of drug produced would result in 6,000 kilos of waste. Why? “Because 80 to 90 percent of the waste is solvent. There are so many different steps required, and each step typically needs a different solvent.” Which is why Prof. Jessop is designing so-called switchable solvents, which – if you add CO2 to the mixture – can be changed into a significantly different solvent and used in the next step of drug synthesis.
Looking ahead
Canadian scientists are also working on turning CO2 into biodegradeable plastics, headed by Canada Research Chair in Green Chemistry Professor Chao-Jun Li at McGill. If successful, his research could forever change the way we make plastics, as well as how we deal with CO2 emissions. Prof. Li is also one of a number of McGill researchers who are using water as a solvent in complex reactions where it was previously thought it could never be used. So revolutionary is this chemistry that it netted Prof. Li a 2001 Presidential Green Chemistry Challenge Award, handed out annually by the U.S. government to academic and commercial researchers who have come up with green solutions to chemical problems. Since 1996, the award-winners have collectively eliminated over 426 million kilos of hazardous chemicals and solvents, saved over 2,270 million litres of water and reduced CO2 emissions to the air by 150,000 tonnes. So important is green chemistry for our technological and ecological future, the 2005 Nobel Prize in Chemistry was awarded to three academics for their work in this field. “All of these success stories represent the tip of the iceberg – we’ve barely scratched the surface of what can be done,” says Professor Paul Anastas, Director of the Center for Green Chemistry & Green Engineering at Yale University and widely regarded as the father of green chemistry. “Green chemistry is about changing our perspective on environmental and sustainability issues from one of fear to one of action. Rather than focus on the problems, focus on the solutions.”
Zoe Cormier is a writer who specializes in scientific, environmental and health-related stories. Her environmental column appears in The Globe and Mail twice monthly.